Nitro Substituted Bisindolylmalimide Derivatives: Position-Dependent Emission

Abstract

A small series of partially alkylated bisindolylmaleimide dyes were prepared containing NO₂ groups at the ortho, meta, and para position. The effect of substitution position in the aryl ring on the photophysical properties of the dyes is discussed in detail. The highly electron withdrawing NO₂ makes different emission behavior of these dyes. Medium quantum yields of fluorescence in toluene solution are observed for derivative with NO₂ substituted in the ortho position of aryl ring. Careful analysis of optimized structure and frontier molecular orbitals (HOMO/LUMO) suggests that the electronic rather than steric effect is controlling non-radiative decay.

Keywords:

• Bisindolylmaleimide
• ortho, meta, and para position
• photophysical properties
• frontier molecule orbitals

Funding

This work was supported by the National Natural Science Foundation of China (grant no. 21072048 and 21272060). This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (grant no. 2013054767).